Nitrate enrichment of larval habitats enhances physiological resilience and reduces insecticide susceptibility in Aedes aegypti (Diptera: Culicidae) mosquito

Abstract Although nitrate is one of the most common fertiliser-derived contaminants in mosquito habitats, its public-health implications for mosquito development and insecticide susceptibility remain poorly understood. This study examined how nitrate enrichment influences biological traits that directly affect vector proliferation and the effectiveness of insecticide-based control strategies. Larvae were reared from hatch across a gradient of nitrate concentrations (0–1024 mg/L) and monitored through emergence. Developmental outcomes (duration of immature stages, survivorship, larval growth rate), metabolic reserves (lipid, protein, glycogen, glucose), susceptibility to permethrin (0.75%), and detoxification enzyme activity (esterases, glutathione-S-transferase) were estimated following standard procedures. High nitrate concentrations significantly prolonged larval and pupal development, while survivorship remained high (> 90%). Larval growth rate peaked at moderate enrichment (16 mg/L). All metabolic reserves increased with nitrate exposure, indicating improved physiological condition. Importantly, nitrate-reared mosquitoes exhibited substantially reduced susceptibility to permethrin and elevated detoxification enzyme activity. These findings highlight nitrate pollution as an overlooked environmental driver that can enhance mosquito robustness and reduce the efficacy of insecticide-based interventions. As nutrient runoff intensifies with agricultural expansion, integrating environmental nutrient management into vector-control planning may be essential for sustaining the impact of current dengue and arbovirus prevention strategies.